The objectives of the proposed research are the determination of the cognitive algebra of area quantification for various geometric forms as it develops in children from the preschool period in which area quantification is severely limited by dimensional centration, through development of dimensional coordination and compensation in simple estimation for simple figures, to combinatorial area computation involving fractionation and multiplication of a given area, and addition or subtraction of more than one area; and the determination of the developmental sequencing and interrelationships of the various integration laws appropriate to the various developmental levels. The methods to be used will be those of information integration theory and functional measurement, using experiments which require simple and combinatorial estimation, laid out in factorial designs which permit testing of algebraic models of the integration law, stimulus and response scaling, parameter estimation, and analysis of variance goodness of fit procedures.